Problem: Simplify the following expression: $r = \dfrac{-4a - 4}{4a - 4} \div 10$
Dividing by a number is the same as multiplying by its inverse. $r = \dfrac{-4a - 4}{4a - 4} \times \dfrac{1}{10}$ When multiplying fractions, we multiply the numerators and the denominators. $r = \dfrac{(-4a - 4) \times 1} {(4a - 4) \times 10}$ $r = \dfrac{-4a - 4}{40a - 40}$ Simplify: $r = \dfrac{-a - 1}{10a - 10}$